Regional characterisation of meteorological drought and floods over west Africa
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(2020) 6:80
ORIGINAL ARTICLE
Regional characterisation of meteorological drought and floods over west Africa Chukwudi Samuel Ekwezuo1 · Christopher Uche Ezeh1 Received: 14 October 2019 / Accepted: 1 September 2020 © Springer Nature Switzerland AG 2020
Abstract West Africa is characterised by diverse hydro-climatic divisions ranging from the humid equatorial climate to the semi-arid and arid climates that manifest in high space–time variability in rainfall. In this study, drought and floods in six delineated domains (Northern Sahel, Southern Sahel, Sudanian, Western Guinea Coast, Central Guinea Coast and Eastern Guinea Coast) of West Africa were illustrated using the Standardized Precipitation Index (SPI 3 months and 9 months) calculated from global CPC Merged Analysis of precipitation (CMAP 2.5° by 2.5° resolution) data from 1980 to 2017. The trend analysis shows that none of the domains exhibits a significant trend in the computed SPI. However, there is a significant trend in the annual rainfall rate for all the domains except the Eastern Guinea Coast. Again, there is a likelihood of an increasing trend of SPI-3 but a decreasing trend for the SPI-9. The drier areas have significant increasing rainfall trend while the highly humid regions show significant negative trend except for the Eastern Guinea Coast that shows a non-significant very weak positive trend. The most exposed area to extreme drought conditions occurs over the northern Sahel domain at SPI-3 though the frequency of occurrence is very low. The Western Guinea coast experiences the highest number of dry events of about 32% of the time followed by the Northern Sahel domain. Under SPI-9, the following domains: Eastern Guinea coast, Sudanian, Northern Sahel and Western Guinea coast are prone to flooding incidence as they had 40%, 37%, 29% and 26% of wet events, respectively. The study recommends apt and timely climate service delivery, adoption of ecosystem-based adaptation strategies that promote apt and sustainable water management practices in the region. Keywords Drought · Flood · Standardized precipitation index (SPI) · Mann–kendall test · Trend analysis · West africa
Introduction Over West Africa like other tropical regions, rainfall is the dominating weather element that defines its climate. The rainfall is highly variable over space and time. Such variability often results in pleasant or unpleasant conditions at multiple time scales with significant impact on the socioeconomic development of the region. Because of this, several researchers have studied diverse aspects of rainfall characteristics of the region amongst which are (Shanahan et al. 2009; Druyan 2011; Daron 2014; Koudahe et al. 2017). One attribute of weather that is of major concern confronting the society and which baffles scientists is its associated extreme events. The occurrence of these extreme events is on the * Christopher Uche Ezeh christopher‑[email protected] 1
Department of Geography, University of Nigeria, Nsukka 410001, Nigeria
increase as climate model projec
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